Cranial bones


Cranial bones by design are a hard shell of an enclosure which protects the brain and its associated nerves, fluids, and other sensory organs. This responsibility is met via the construction that is created through the frontal, two temporals, the occipital, the sphenoid, as well as the ethmoid bones.


The frontal bone is used to create the roof of the enclosure, which by default also creates a forehead. Through its design the top of the nasal cavity and top arches for the eye sockets are formed as well. The frontal bone is located in the anterior of the structure, thus its name.

Before the age of five or six, the frontal bone is actually two frontal bones that eventually go through the process of ossification and form one solid fused bone. While fusion may complete early in life, sometimes a suture is left behind which is known as a metopic suture. No harm is caused by this suture.


Cranial bones
Image: Cranial Bones

The supraorbital margin, which is commonly associated with prehistoric humans and the ridged eyebrows, is still visible in present day human life. The ridge is prominent and still resides over the orbital cavity. The supraorbital foramen, which can be found just mildly medially to the midpoint of the supraorbital margin, is a tiny crevice like opening which is designed to allow the free flowing passage of veins, arteries, and nerves.


The frontal bone also helps in the creation of the facial structure that develops the frontal sinuses, which connect directly to the sinus cavity. Sinuses assist the skull not only in the creation of the cavity which is responsible for structures as they relate to breathing, but also reduce the weight associated with the skull. The sinuses also assist in the process of sound resonation, which in turn produces vocalization.

There are two parietal bones which create the roof like structure of the cranium as well as the very top of the sides of the skull. These bones are segregated from the frontal bone by a suture, the coronal suture, and the additional suture known as the sagittal suture segregate the right parietal bone from the left. These cranial bones, along with the other bones which comprise the cranium, are marked by what seems like random concave divots throughout the skull. These concave divots represent the impressions created by the convolutions of the brain and various vessels which help maintain the brain.
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